* EU regulator says 16 cases in Europe, 8 in U.S., 4 deaths
* Shares in Elan touch year-low; Biogen down 0.7 pct
LONDON, Oct 29 (Reuters) - European regulators reported another case of potentially deadly brain infection in patients taking multiple sclerosis drug Tysabri, taking the worldwide total since 2006 to 24.
There have been four deaths, a spokeswoman for the European Medicines Agency said on Thursday.
The European Union accounts for 14 of the cases of progressive multifocal leukoencephalopathy (PML), with two in Switzerland and eight in the United States.
Last Friday, the agency announced it had begun a review of the drug after reports of 23 cases of PML, sending shares in the drug’s makers Biogen Idec Inc (BIIB.O) and Elan Corp Plc ELN.I sharply lower. [ID:nN23102944]
Tysabri was temporarily withdrawn from the market in 2005 after being linked with the disease. It was reintroduced in July 2006 with stricter safety warnings.
Elan fell as much as 3 percent to a new year low on Thursday, before recovering, while Biogen was down 0.7 percent by 1615 GMT. (Reporting by Ben Hirschler; Editing by David Cowell)